This invention relates to electronic musical instruments, and more particularly to a control effected in ending the generation of a musical tone amplitude envelope in an electronic musical instrument.
In generating an envelope waveform with a digital type electronic musical instrument, the amplitudes of the envelope waveform at sequential sampling points are stored in an envelope memory, and a counter controlling a memory reading operation is driven with the aid of predetermined clock pulses so as to successively advancing the addresses to be read out of the memory storing the sampling point amplitudes. Accordingly, the envelope waveform is generated stepwise. The modulation of the amplitude of a musical tone waveform (or a tone source waveform) is effected in accordance with the shape of the envelope waveform.
The envelope waveform is in the form of steps, as described above. Therefore, when the generation of the envelope waveform is finished at the last step thereof, the level of the envelope waveform as shown in FIG. 1(a) is lowered abruptly to the zero level from the level L of the last step. If the instant when the last step of the envelope waveform falls to the zero level corresponds to such a phase of the musical tone waveform signal that exhibits its maximum or nearly maximum amplitude, the amplitude of the musical tone waveform signal is lowered abruptly to the zero level. As a result, upon termination of the tone production (or termination of the envelope form generation) a click sound is produced.